Information

STUDY OF CHILDHOOD LEUKAEMIA NEAR
POWERLINES PUBLISHED IN THE BRITISH MEDICAL JOURNAL
by Draper G., Vincent T., Kroll M.E. and Swanson J.,

Friday 3rd June 2005

BMJ 2005;330;1290-doi:10.1136/bmj.330.7503.1290

‘Findings of higher childhood leukaemia up to 600 metres from powerlines greatly extends findings from previous international studies, including those in the UK’, says Bristol Professor

The findings by Dr Gerald Draper and colleagues of increased rates of childhood leukaemia up to 600 metres from high voltage powerlines in the UK, published in the British Medical Journal today, greatly extends previous findings from a pooled analysis of international studies which included the results of a previous UK study.
Denis Henshaw, Professor of Human Radiation Effects at the University of Bristol said today:

“These latest findings not only strengthen further the evidence that children living in proximity to high voltage powerlines are at increased risk of childhood leukaemia, but in finding effects up to 600 metres away, they invoke electric field corona ion effects as a possible causal mechanism. The fact that this study has looked at the birth address is particularly important because the initial damage that may lead to leukaemia is thought to occur in-utero.”

While the number of excess cases of the disease in children living near powerlines may be around 5 per year, this may be the tip of the iceberg: (i) in terms of the extent to which both the magnetic fields and electric fields associated with the electricity supply may be a factor in the incidence of childhood leukaemia, and (ii) in terms of the many other illnesses also associated with magnetic fields such as adult leukaemia, adult brain cancer, miscarriage and depression.
A particularly important finding from Dr Draper’s work is the increase in childhood leukaemia up to 600 metres from powerlines, well beyond the range of powerline magnetic fields. In order to understand this finding we need to consider the separate effects of the magnetic fields and electric fields associated with powerlines.
For the magnetic fields, studies in human populations have shown that such fields are capable of disrupting the night-time production of the important hormone melatonin in the pineal gland. Melatonin is a particularly powerful antioxidant which acts as a natural anti-cancer agent in the body. Studies have shown the hormone to be highly protective of oxidative damage to human blood cells - the sort of damage that could lead to leukaemia.
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However, powerline electric fields act differently. The intense electric field on the surface of powerline cables is sufficient to ionise the air, producing so-called corona ions. This process is the cause of the characteristic buzzing or crackling of powerlines. Corona ions are small electrically-charged particles which, when emitted from powerlines attach themselves to particles of air pollution, making these particles more likely to be trapped in the lung when inhaled. In this way people living near powerlines may be exposed to increased levels of air pollution. Crucially, corona ions can be carried several hundred metres from powerlines by the wind, so effects may be felt much further away than for magnetic fields.
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Professor Henshaw said:

“In principle, corona ion effects could well explain the profile of increased incidence of childhood leukaemia up to 600 metres from powerlines”.

Professor Henshaw is available for interview on: 0117 9260353; 0777 3356442; email d.l.henshaw@bristol.ac.uk or the University Press Office 0117 3317276
More information on the research in Professor Henshaw’s team may be found on their website:
http://www.electric-fields.bris.ac.uk. The work of Professor Henshaw’s team is funded by CHILDREN with LEUKAEMIA, Britain’s largest charity devoted to understanding the causes
and prevention of childhood leukaemia.

Notes for Editors

1. Corona ions

Corona ions are routinely emitted from high voltage powerlines, especially in wet conditions outdoors. In the 1950s, corona ions effects were measured up to 7 kilometres from powerlines both in the UK and in Germany. In today’s conditions, we have measured corona ions up to 7 kilometres from a high voltage powerline near Glastonbury, Somerset. We have previously estimated that on average corona ion effects, significant to adversely affect human health, extend to 400 metres from powerlines. In this regard, the findings by Dr Draper of increased childhood leukaemia up to 600 m from powerlines in clearly significant.

2. Other background information

In Autumn 2000, a pooled analysis of international studies on electric and magnetic fields (EMFs) and childhood leukaemia, led by Professor Ahlbom of the Karolinska Institute in Sweden, which included the results of a study in the UK, was published in the British Journal of Cancer in 2000 (Vol. 83, pp 692-698). The study showed that children exposed to magnetic fields above a level of 0.4 microtesla were at twice the risk of contracting the disease. While this level of exposure is above average levels found in the home, it is well below levels found near high voltage powerlines where values can reach several microtesla or even tens of microtesla. The Ahlbom study has since led the International Agency for Research on Cancer (IARC) to classify magnetic fields as a possible carcinogen and the World Health Organisation to call an international meeting to discuss the issue of introducing precautionary measures against exposure to EMFs associated with the electricity supply. Last year, the then Public Health Minister, Melanie Johnson, set up a Stakeholder Advisory Group on EMFs (SAGE) to examine the issue of precaution against EMF exposures in the UK.

In June 2002, a major report on EMF health effects from the California Health Department found increased risk of childhood leukaemia, adult leukaemia, adult brain cancer and miscarriage. This report may be accessed at:

Childhood leukaemia is a mercifully rare disease, which constitutes about one third of approximately 1400 cases of childhood cancer per year. The number of cases associated specifically with powerlines is small in absolute terms but the number associated with the electricity supply generally is not known. Childhood leukaemia is a biologically diverse disease and is likely to arise by several aetiological pathways. A number of factors are
associated with the disease, such as infections, background radiation, magnetic fields, air
pollution and paternal pre-conceptual exposure to hydrocarbons.